I just had a free month on them. It was great but for me the plans are weird. 300 searches a month is _probably_ enough but the fact that I'm on a countdown makes me super cagey with my searches. And I want to want to use the service if that makes sense. I'm not opposed to paying (I pay for email) and I know they share the reasons for the pricing, but my email account is something like $3 a month.
I guess this is a long winded way of saying I'm cheap? I'm close to the fence but thus far have stayed on the far side mostly due to price. At $5 a month unlimited I'd be in for sure and probably usually not hit the 300 number. The AI included level is intriguing though.